Picture by joelwillis via Flickr (Creative Commons 2.0)

I usually don’t like making grandiose statements ahead of myself, like “Astrology is totally unscientific”, because I prefer leaving the benefit of the doubt until I check the claim. In the case of Astrology, however, there’s no use pretending.

Astrology isn’t science. It makes baseless predictions, relies on overly-generalized statements and has a false basic premise*.  You can read this online from various other sources, and there isn’t much use for me to reiterate the points made.

What I am going to do is test the basic premise.

* Phil Plait, “The Bad Astronomer”, has a great analysis of Astrology that goes over all the above, and more, as does the skeptic dictionary and the Astronomical Society of the Pacific among many, many others. You can also watch Australian Skeptics’ Richard Saunders brief live argument with an Astrologer.

Note: For your convenience (and due to popular demand), I added an automatic tool where you can measure the force applied by any object at any distance. Test it yourself!

Click here to open the Force Calculator!

(opens as a new window).

The basic premise of astrology

Astrologers claim that the positions of the planets and “Zodiac” signs (constellations of stars) at the moment of our birth – and generally throughout our lives – affect our personality, mood and affairs.

I will not get into the so-called  “metaphysical” effects, a mishmash of misunderstood physical theories (quantum physics, dark matter, dark energy, etc) with some pseudoscientific new-age unfalsifiable claims (from “fate” and “luck” to “planetary energies”, whatever that means). What I will do is treat the claim that astrology has merit in science. Many astrology-believers think that since the planets exert gravity, they might affect our brains, and therefore our moods.

Many people give the moon as an example. The moon’s gravity is known to affect tides – a powerful force we can witness. Many take this as proof that the planets’ gravity is affecting our bodies. On its face, the claim makes sense.

We are going to examine it.

Gravity, the force of masses

Any two objects with mass exert gravitational force on one another. That force is related to the masses of the objects and the distance between them by the formula:

Where G is the universal constant of gravitation, M and m are the masses of the objects and r is the distance between them.

Since we think of planets as incredibly big objects, the idea that their gravity affects our bodies sounds reasonable. But to a newborn, there are other “massive” objects around that exert the same type of force as the planets. They might be much smaller than the planets, but they are much closer, too. If the position of planets at the moment of our birth defines our personality, so should the positions of objects in the delivery room.

This is a testable claim.

The test: planets vs. delivery room

We are going to compare two forces, those coming from the planets and those coming from objects in the delivery room, to reach a conclusion:

• If the forces from the objects in the delivery room outweigh those from the planets, then astrologers should, at the very least, ask the weights and positions of the people in the delivery room when they calculate your chart.
• If, however, the forces of the planets are substantial, then astrology might have some scientific merit. This is what we are about to check.

OMG! Math! Panic!

Relax.

We are about to calculate physical forces so there is some math involved, but you can choose if you want to see it or not. Yes, I’m that considerate.

If you want to go over my math so you can repeat it yourself, add to it (items I missed?) or criticize me (peer-review away, mathematicians) you can reveal the calculations by clicking the “Show the Math” links.

Otherwise, just continue reading the solutions only. Those are useful too.

kthxbai!

One more note: Forces are directional (vectors), but in this case, since we want to calculate the maximum possible force, we will treat them as if they are “lined up”, and therefore calculate them numerically.

What about the mother?

Right, the mother is also in the room, and her body also exerts a gravitational force on the baby. However, The baby is inside the mother, and in her midsection. He is, almost literally*, in her center of mass. For all intents and purposes the mother’s gravity “cancels out” from all directions and there’s no use adding her into the calculation.

* Physicists, stay calm, think “spherical chicken in a vacuum” and bear with me here.

On we go.

The delivery room

Since my intent is to calculate the most basic hospital delivery room, I put in the most basic items that should be found in one. There are likely many more people and pieces of equipment in and outside the room, but the goal of these calculations is a “conservative estimation.”

Therefore, I will ignore the size of the hospital, other people walking by and other large machines that exist in the building. See “Conclusion” for more about those.

Here’s a list of what should be the most basic elements in a delivery room:

People:

• A doctor (obviously)
• A nurse
• OB tech (whose job is to help the doctor and nurse during the actual birth)
• The partner (assuming the mother has one)

Objects

• Bed or birthing chair.
• The machine that beeps (heart monitor).
• Baby crib
• Scale (to weigh the baby, clean and check him or her up)
• Sphygmomanometer (blood pressure monitor) and stethoscopes.

The Calculation

In the following section I will calculate the force exerted on the baby from each of these elements by estimating their weight and mass and their relative distance.

I will assume average-sized staff (75-85 kg), leaning towards the thinner side, to keep my estimate conservative. I will also assume that the baby is level with their midsections (i.e., their centers of mass) which will allow me to ignore their height in my calculation.

Show the Math

Total Maximum Force

So, to summarize (and, for those of you who cared not for the mathematics, to state in the first place):

• The Doctor =
• The Nurse =
• The OB Tech =
• The Partner =
• The Bed =
• Heart Monitor =
• Scale =
• Other Small Objects =

Show the Math

Total Force:

The Planets

EDIT: I have recalculated the forces from the planets. It seems that during the initial calculations I made a rather small (but recurring) conversion error, and due to vigilant commentors, it was properly corrected. You should note, though, that the total force after this re-examination didn’t change. My calculation was fine, I just had a problem with how I wrote it out in the process (in the math part). Apologies.

Now, astrology claims that the planets exert a force on the baby, and their different locations change that force ever-so-slightly to somehow affect the baby’s personality traits.

The idea that the planets exert a force, even on the baby, is true. Whether or not it is canceled out or overwhelmed by other forces is a different issue.

Our next step, then, is to calculate the maximum force that can be exerted from the various planets, and combine them to get the maximum possible force exerted by the planets.

Show the Math

The force from all the planets combined

All of the forces above were calculated as if the planet is in its closest position to the Earth. The chances that all planets together will be in such positions are incredibly small. This doesn’t usually happen, and the resultant combined force is much smaller. However, we can still calculate the maximum theoretical force that can be produced by all planets combined on the newborn baby.

Here they are:

• Mercury =
• Venus =
• Mars =
• Jupiter =
• Saturn =
• Uranus =
• Neptune =
• Pluto =

(Before you protest about Pluto, read this: there are many problems with including Pluto in the calculation of gravity – the least of which is his “partner” Charon, who’s of similar mass. However, Astrologers calculate Pluto into their maps, and so I thought it would be appropriate to include the force it exerts, too.)

Show the Math

Total Force =

Comparison

So, what do we have?

• The combined forces of the delivery room =
• The combined forces of the planets =

Difference =

The forces from the delivery room are 8 times bigger than the combined force from the planets, and we have calculated a very conservative estimate.

Proponents of the claim might jump out of their seats and claim the forces are extremely close. They seem close (if a factor of 8 is considered close) but we have to remember a few important issues that show conclusively that the forces from the planets are minuscule compared to the forces exerted on the baby from his immediate surroundings:

• The planets do not, ever, line up where they are all as close to Earth as our calculation asserted. The realistic force from the planets is lower.
• Our estimates for both the distances, the amount of people and their weight was very conservative. In reality, hospitals have a lot more people and staff, much more equipment in the room and directly outside of it.
• Hospitals are huge places. If planets as far as a few billion kilometers exert force on our newborn baby, the MRI machine (that weighs 50-60 times the weight of the doctor, nurse and OB Technician combined) at some floor below, and the CT machines somewhere in the hospital should be taken into account as well. Those would dramatically increase the difference between the two forces.
• And, one of the most notable point of all: We ignored the Earth’s gravity!

We ignored the Earth’s gravity!

To be fair, I ignored the Earth’s gravity in both cases, for a very good reason: it absolutely trumps both. Since it is also coming from the ground, and the other forces are spatially distributed, my goal was to show that even without gravity, the difference exists, and is indeed noticeable.

But the Earth’s gravity is important here.

The Earth isn’t a perfect sphere; its radius varies from 6357 km to around 6378 km.

Assume the baby is 6360 km from the center of the Earth.

Show the Math

In this case, the force exerted on him by gravity would be

As you can see, this is times more than the forces exerted by the occupants of the delivery room, and times more than the force exerted by the planets together. It’s a powerful force, gravity.

And there’s more. The Earth’s gravity isn’t constant. It varies across the surface of the planet (as the radius varies). We usually use the average rounded number for the gravitational acceleration () but in different locations on the Earth, the number varies.

If the claim astrologers make is that the force from other planets affect a baby’s personality – and we’ve seen how small that force is! – then the change in the Earth’s gravitation should have an effect too. In this case, Astrologers should consider the location and elevation of your birth as well as the date and time, to calculate the variations in the Earth’s gravity.

The next time an Astrologer offers to calculate your chart, you should reminder them about that.

One more thing: The Labor Itself

We didn’t include this part in the initial calculation, but this is definitely something that we should take into account, since this is likely to be quite a powerful force.

A baby doesn’t just “walk out” of the womb, it is pushed out by the mother’s muscles. If you see any TV shows at all, you know that at the moment where the baby – and doctor – are ready, the doctor will ask the woman to “Push!!” resulting in the baby’s head being pushed out (if all is well) and the doctor assisting the baby the rest of the way.

This “push” and the movement out of the woman’s womb also exert force on the baby. On top of that, there is usually a large amount of time during which the woman’s body exerts force on the baby before it actually comes out. This would apply pressure on his body; obviously, it’s not enough to harm the baby, but it definitely exists. And labors can be long… long and tedious processes. Ask your mother how long she was in labor.

So for a large number of hours (36 is the average!) the baby is subjected to pressure from the mother’s contractions, and then to the force that pushes him or her out of the womb.

So.. why don’t Astrologers ask how long your labor lasted?

Conclusion

There are many things that are plain false in the claims that Astrologers make, and many blogs and sites covered the reasons why. Now, though, you could see for yourselves how the basic premise – that planets’ positions, affect the personality trait of a newborn baby – is just silly.

If the planets’ positions affect the baby’s personality traits, so should the Doctor’s position, the OB Technician, the position of the heart monitor, the CT machine down the hall and the size of the hospital and the amount of people in it.

So, unless Astrologers are willing to take these components into account when they produce your “Chart”, it seems their claims are plain silly.

And you should tell them that.

Do you have more objects to test?

Now you can. Due to popular demand, I’ve prepared a small tool to help you calculate the force from object at any distance. Play with it, and share your findings in the comments!

Click here to open the Force Calculator!

(opens in a new window).

Resources

• http://pregnancy.about.com/cs/laborbasics/a/aa021504a.htm
• Labor and Delivery Room (scribd): http://www.scribd.com/doc/6390726/Labor-and-Delivery-Room
• Monty Python’s Hospital Sketch http://www.youtube.com/watch?v=arCITMfxvEc
• Average fetal weight: http://www.babycenter.com/average-fetal-length-weight-chart
• http://nssdc.gsfc.nasa.gov/planetary/factsheet/
• http://www.universetoday.com/guide-to-space/venus/venus-distance-from-earth/
• http://www.universetoday.com/guide-to-space/mars/distance-from-earth-to-mars/
• http://www.universetoday.com/guide-to-space/jupiter/how-far-is-jupiter-from-earth/
• http://www.universetoday.com/guide-to-space/saturn/saturn-distance-from-earth/
• http://www.universetoday.com/guide-to-space/uranus/uranus-distance-from-earth/
• http://www.universetoday.com/guide-to-space/neptune/how-far-is-neptune-from-earth/
• http://www.spinlife.com/Drive-Medical-600-lbs.-Bariatric-Full-Electric-Frame/spec.cfm?productID=82578
• Stages of Labor: http://www.accd.edu/sac/nursing/rnsg2261/PDFWH/StagesOfLabor.pdf

Thanks

Once again, thanks goes to:

• Capn_Refsmmat, for some language issues, for his mastery of the LaTeX plugin and for his math peer-review.
• Daniel Grrrrrr for his English support and patience. Lots of it.
• UnintentionalChaos (from ScienceForums.net) for some math peer-review and clarity correction issues.

The “losing weight” trend is one of the better outcomes of reality TV, and it encourages people to take charge of their lives and live a healthier life.

But there’s one thing that bugs me about this trend: The terminology.

Folks, you lose weight every time you go down a fast elevator. What you actually want is to lose mass. Since your weight is affected by your mass, it will mean that your body will weigh less on the scales the less massive it is, but the goal is not your weight, the goal is your mass.

“Burning fat” and getting rid of excess calories along with training in the gym will make you leaner, thinner, and less massive.

The force that a leaner body exerts on the floor is less than the force a big body exerts on the floor, but what you work on when you want to “lose weight” is, in fact, shaping your body’s mass: losing the mass of fat and/or gaining the mass of muscle.

I can lose weight without touching my mass by simulating a “weightlessness” situation, or by getting close to it.

For example, try riding up and down an elevator while standing on a scale.

When the elevator accelerates downwards, it is moving away from your feet and your body is, essentially, in a condition of “falling”. That decreases the force it exerts on the floor, and you experience a state of semi-weightlessness, depending how strong the elevator’s acceleration is.

When the elevator accelerates upwards, the force your body exerts on the floor is now increassed, because the floor goes up faster than your body can chase it, and your feet are pushed down towards the floor.

Congratulations, you just gained and lost weight in a few minutes.

If you want to be lighter, jump off a plane (with a parachute, please). The state of a ‘free fall‘ your body will be in for the first moments will simulate weightlessness. In these situations your weight is zero, but your mass -- the particles that make you “you” didn’t go anywhere.

And though you just lost weight, that does not make you thin.

The term “Weight Loss” is so engrained in our society, that it will be futile of me to try and get you to stop using it. That does not mean, however, that you can’t understand the physics behind those terms.

So, remember: If your goal is to lose weight, ride down an elevator or jump off a plane with a parachute.  If your goal is to be leaner, excercise and eat right, and get rid of that mass of fat that surrounds your muscles.

Alternatively, you can go live on the International Space Station, where weight is not an issue.

Resources and References

• Weightlessness in Wikipedia: http://en.wikipedia.org/wiki/Weightlessness
• “The Biggest Loser” show: http://www.nbc.com/The_Biggest_Loser/

Credits

• Music from http://www.freeplaymusic.com
• “Houston” Mission Control voice: Daniel

Picture Credits (used in the video)

• I heart Nerds T Shirt http://www.flickr.com/photos/elvissa/880588709/
• (Featured photo) Scale http://www.flickr.com/photos/restlessglobetrotter/2929270640/
• Hamburger http://www.flickr.com/photos/jesswebb/2633566137/
• Obese dog http://www.flickr.com/photos/34428760@N03/3202436425/
• Lean dog http://www.flickr.com/photos/draplin/912213752/
• Pyramid http://www.flickr.com/photos/swamibu/2223726960/
• Sky scraper http://www.flickr.com/photos/nogood/220232524/
• Jumping off the roof http://www.flickr.com/photos/paulbence/93988862/
• Elevator free fall http://www.flickr.com/photos/bass_nroll/2215862793/
• Rollercoaster http://www.flickr.com/photos/mprinke/1139986131/
• Gym http://www.flickr.com/photos/abraj/181196330/
• Veggies http://www.flickr.com/photos/valjk/634696442/
• Obesity http://www.flickr.com/photos/combinedmedia/3067501298/
• Iron man http://www.flickr.com/photos/sscusp/242103879/
• Big man with coke http://www.flickr.com/photos/fatmandy/165144643/
• Weight loss http://www.flickr.com/photos/vernonwhite/3327754571/
• Baby cringe http://www.flickr.com/photos/craigforsyth/2384364393/
• Skydiving http://www.flickr.com/photos/gogap/423485388/
• Leaner http://www.flickr.com/photos/christinielsen/97438813/
• Exercise http://www.flickr.com/photos/n8kowald/1467191600/

A little while ago, the Israeli Museum in Jerusalem opened an exhibit featuring some of the torn, slightly burned pages of Col. Ilan Ramon’s personal diary from the shuttle Columbia. Ramon was the payload specialist onboard STS-107 (the spaceshuttle “Columbia”) that disintegrated during re-entry from space, killing all 7 crewmembers onboard. The diary survived the re-entry and subsequent crash, and was found in a field next to Palestine, TX.

Ramon’s personal diary fell close to 37 miles (almost 60 km) through the extreme conditions of re-entry. Unlike its human owner, it has survived the process and is now being restored and presented to the public in the Israeli Museum in Jerusalem.

During the weeks and months after the Columbia disaster, pieces of the debris were still being collected from wide areas in Texas. small pieces of insulation that detached from the outer parts of the shuttle to pieces of the Astronauts’ space suits. In an article covering the subject on “Universe Today”, The Israeli Museum curator is quoted as saying that “There is no rational explanation for how it was recovered when most of the shuttle was not.” It is no wonder, then, that many are awe-struck at such an apparent miracle.

But is there, really, no rational explanation for the survival of the diary? None at all? I doubt that. And when I doubt, I check it out, which is exactly what I am about to do.

A thought (or two) about Hypotheses

The information about the Columbia disaster is available in many online and offline sources, but it is still very limited. We can guesstimate what happened to certain parts of the shuttle based on facts on the ground and what we already know from previous manned missions to space using the Columbia shuttle.

The general investigation I am about to embark on in this post is based on the material I have found online and my own personal knowledge, strengthened by facts from other missions and physical concepts. It is by no means complete, and I had no time (or resources, sadly) to do a full blown investigation into the full train of events that Col. Ramon’s diary went through. If you have any thoughts on the matter, or if you hold any factual data that will help hypothesize what it “went through” in the moments before hitting the ground, please share them in the comment section. I am very much willing to update and upgrade this hypothesis in light of new information or ideas (just make sure you base those on valid data, of course).

I try to support my guesstimates with valid data when I can, and use ‘extremes’ to get us a rough idea of how this discovery (and this ’survival’ of such an item) is possible.

The Space Shuttle – Crew Quarters

The space shuttle is built to sustain its crew for days (and sometimes weeks) in space. It has sleeping bunks, restroom and shower, all located in the crew area in the “Mid Deck” (picture is taken from Space Shuttle News Reference (NASA), p 5-5):

According to ex-astronaut R. Mike Mullane, the mid deck also holds the crew personal lockers (“Do Your Ears Pop in Space”, R.  Mike Mullane, pg 135). We will remember this fact when we consider the process in which the Columbia disintegrated (keep reading).

Where was the Diary Located?

No one can know for sure (at least not from the published data that I’ve read) where the diary was located before the Columbia’s disastrous descent. However, there are a few facts we can be sure of:

• The crew was about to come home; their personal items were, most likely, locked away in their personal lockers, that are located in the Mid Deck.
• According to astronauts who were active in previous missions, a diary is sometimes put in the lower pocket of the flight suit. If the diary wasn’t locked away in Ramon’s personal locker, it is logical it was safely tucked into his flight suit pocket.  Flight suits are very durable and tolerate extreme heat and cold conditions.

Either way, it seems logical to assume that the diary was placed somewhere that kept it safe from the initial processes of re-entry and descent.

Temperature Variation

Unlike common belief, the intense heat on the wings and body of a space shuttle as it descends from Space is not caused by friction, but rather by ‘compression’. The big body of the shuttle compresses air molecules downwards so strongly that the air around the shuttle becomes dense and packed like plasma. At this point, the wing-edge temperature naturally rise, and can reach a temperature of about 1,400° Celcius (2,500° Fahrenheit).

After the initial temperature rises, the Columbia initiated a roll to the right, a maneuver that decreases its speed and the heat on its body. This maneuver was successfully performed, and following it were 10 minutes where the heat on the body of the shuttle reached its peak. From there, it started to cool down.

The temperature at these heights is extremely low, and the heat from the shuttle can dissipate relatively quickly.

Explosion vs. Disintegration

About 15 minutes after the Columbia entered the Earth’s atmosphere, pieces of debris were visibly shedding out of its body. But the Columbia did not explode, it disintegrated, and this difference is very important to understand what happened to the parts inside the shuttle.

Explosion and Disintegration are two very different processes.

• Explosion (from Merriam Webster Dictionary):a large-scale, rapid, or spectacular expansion or bursting out or forth.
• Disintegration (from Merriam Webster Dictionary): 1 : to break or separate into constituent elements or parts 2 : to lose unity or integrity by or as if by breaking into parts.

Explosion is quick and “dirty”, resulting in a lot of damage to the individual parts. Disintegration is the breaking apart of the whole into individual, smaller, parts. It is usually slower, and gradual. The Columbia’s disintegration began about 10 minutes after re-entry and lasted until the massive body crashed on the surface. The various parts and debris were scattered over an enormous area, from eastern Texas to Western Louisiana.

The fact that the Columbia disintegrated, rather than exploded, has two main meanings for our investigation:

1. The Columbia did not ‘explode’ all at once; it took time for the various parts to separate away from the main body while the shuttle was cooling down in descent.
2. In an explosion, the parts heat up due to the exerted energy. When a body disintegrates, the parts separate away from the body without experiencing any sort of extra heat. If a piece was deep inside the shuttle, it wasn’t subjected for the intense heat from the plasma (during re entry). It would take it longer to be thrown-away and out of the body of the shuttle. It would, therefore, “spend” less time free-falling.

The objects inside the Columbia slowly broke apart and began a gradual free-fall to the ground, from varying heights, the largest of which is approximately 60 km above the surface of the Earth.

Disintegration = Change in Shape

The shuttle is designed and built for aerodynamic movement. From the nose, to the wings and tail, the purpose is to make sure its movement in the air is smooth and with as little drag as possible. This is meant to decrease drag and allow the pilot better control over the movement of the shuttle once it’s back inside the atmosphere.

Aerodynamic objects move very quickly through the air because of their shape. But Columbia began disintegrating about 40 minutes after initiating the ‘de-orbiting’ maneuver. Parts tore off its body, probably starting with the wings and tail (that ’stick out’ of the body and are subjected to more heat and pressures). Once those pieces – and pieces of the outer hull – tore off, the Columbia lost its aerodynamic shape. From this point on, it will slow down dramatically.

Terminal Velocity of an Object

In reality, when an object falls from a certain height down to the ground, its velocity increases because of the pull of gravity. Air resistance, however, exerts a force upwards – “fighting” the downward acceleration. When both forces are equal, they both negate one another, and the object falls in a constant speed (without the effect of any acceleration). That speed is called ‘terminal velocity‘.

For example, a sky diver falling from 12,000 feet would stop accelerating (hence, would move at a constant speed) at about 200 kph (124 mph). If his parachute didn’t open, he would hit the ground at the same force that a motorcyclist going at 200kph would hit a cement wall in case of a head-on collision (don’t try this at home). The height, in the case of the speeding diary, is not a very good indicator as to the force it hit the ground with.

Terminal Velocity and the Falling Diary

Assuming the diary was protected during the initial stages of the disastrous descent (as I’ve already explained), it shouldn’t have fallen as fast as it may sound like. When we hear the height “60 km above ground”, it sounds as if the falling object would hit the ground at enormous speed (and force). That, however, isn’t the case, because of the terminal velocity.

It is very much possible that the diary was packed or partially protected during parts of the fall, stopped accelerating at the terminal velocity. The pieces continued to disintegrate as they fell, and at some point whatever ‘protected’ the diary disintegrated and exposed it to the full force of the fall. But by that time the conditions that existed at the beginning of the fall were considerably lessened.

Conclusion

• Based on past missions and the structure of the Space Shuttle, we can safely assume the diary was encapsulated inside an item that protected it, either a closed locker or a sealed space suit pocket.
• Air resistance (and the laws of physics) makes the speed of falling objects limited.
• The diary was found in a damp field covered with soft leafs (provided a relatively soft landing).
• Other pieces of debris survived the long extreme fall to Earth (see next section).

Based on all the above, it is a bit easier to see a logical trail of events that could lead to the survival of a paper diary. This isn’t a miracle; it’s a surviving piece of history in light of a horrible, disastrous space mission.

A bit of Realism (Other objects made it, too..)

So we’ve examined the situation, and saw that it’s not as unlikely as we might have first thought for such an item to survive the Columbia disaster. A lot of other debris have survived, including ’sensitive’ materials such as CPU boards and pieces of cloth from the astronauts’ uniforms and rest area. But we also need to take into account the condition in which the diary was found.

According to the State of Israel Ministry of Public Security, which was responsible for the reconstruction and preservation of these pages, the diary was very hard to decipher. It was found wet, torn and crumpled in a muddy field (see picture). The efforts involved a lot of digitized reconstruction along with some measure of guesswork. Some of the text on the pages was simply incomprehensible.

That said, it is also important to remember that this is not the most “surprising” piece of debris that “survived” re-entry. If you want surprise, it is reported that a few worms survived re-entry and the fall to Earth. Yes, alive. A piece of crumpled, wet, torn paper, as emotional and touching as it may be (and I agree that it is), is hardly any competition to life forms surviving the fall to Earth.

This is no miracle.

Many thanks to Capn_Refsmmat for (again!) being the brevity King, and for asking questions that needed to be answered.

References and Resources

• The Physics of Space Shuttle Re-Entry: http://www.bbc.co.uk/dna/h2g2/A6381038
• Report of Columbia Accident Investigation Board, Volume I: http://www.nasa.gov/columbia/home/CAIB_Vol1.html
• Space Shuttle Orbiter Specifications: http://en.wikipedia.org/wiki/Space_Shuttle_orbiter#Specifications
• Columbia Accident Investigation Board (Official Site): http://caib.nasa.gov/
• STS107 Reentry Timeline:

  http://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaster#Destruction_during_re-entry

• Space Shuttle Blueprints: http://www.militaryfactory.com/blueprints/spaceshuttle.asp
• Space Shuttle Operational Book: http://spaceflight.nasa.gov/shuttle/reference/sodb/
• Columbia debris adds to re-entry research: http://www.msnbc.msn.com/id/5333706/
• Columbia Breaks Up During Reentry; NASA Fears Crew Lost: http://www.spaceref.com/news/viewnews.html?id=722
• Israeli Ministry of Public Security: http://www.mops.gov.il/nr/exeres/BD8C3AB6-6D05-462F-91B3-AA98E3986B24.htm

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Many sites out there reiterate the controversy, but few actually explain what and why it is. In other words: What, really, is the effect of a swimsuit on a swimmer? Why would it give an “unfair advantage”? Can a “Space-Age” swimsuit help Michael Phelps reach his 8-medal dream?

Speedo LZR Racer Swimsuit Official Webpage

Since this subject raises some controversy and doubt, I decided I should check it out. I went to Speedo’s official website and read through all their specifications for the Speedo LZR RACER swimsuit (the source of the controversy, and the one Michael Phelps is wearing) and examined each feature.

But First: Physics in a Nutshell

When looking at moving objects (like balls, or planes, or rockets, or swimmers), there are forces at work. The swimmer exerts force forward and spends energy “fighting” whatever other forces that might be applied in the opposite way.

In physics, in order to predict the speed or acceleration of a certain object, we can draw a rough schematic of the known forces that apply on the object. The sum of all the forces (forward, backward, up, down, diagonal, etc) is the final force.

For more on what a Force is, click here.

About Friction and Drag

In general, every moving object (unless it is in a vacuum, which is very hard to achieve) is affected by friction. The amount of friction depends on the material that the movement is performed on. Ice has a relatively low friction, while cement has a relatively high friction.

Drag is very similar to friction; it is a mechanical force (see above figure) that is exerted on a solid object moving through liquid. The interaction between the moving object and the liquid that it moves through creates a “backwards” force that slows that object down. That force is drag.

Drag depends on the shape of the object and its aerodynamic form. Bulky objects will “suffer” more drag and will be slowed down quicker. Slick objects will have less drag.

That’s why the dog (furry and bulky) can’t swim as fast as the shark (slick and aerodynamic). Poor, poor dog.

The Speedo LZR RACER’s Features, Explained

LZR Pulse:

The official website claims that the suit is made of “ultra lightweight, powerful and water-repellent” material, and that it reduces “muscle oscillation and skin vibration”, which in turn leads to “low skin friction drag”.

The LZR Pulse swimsuit claims to shape the swimmer’s body, forcing his (or her) muscles and skin into a bullet-shape aerodynamic structure that reduces the drag – and allows the swimmer to move faster while expending less energy.

The water-repellent feature of the swimsuit essentially causes it to have less interaction with the water. Since drag is caused by the interaction of the swimmer and the water, this feature will reduce the drag (and friction) even more.

Finally, as you could see in the video (embedded at the end of this post, produced by Speedo), the swimmers’ muscles oscillate — move back and forth quickly — while water is flowing at them.

This muscle-oscillation causes the muscles to change shape, which causes the aurodynamic property of the swimmer’s body to change also. In order to maintain the ideal aerodynamic shape, the swimsuit holds the muscles tightly and produces a slick, stable surface that reduces surface tension, increases the velocity of the water flow next to the body, and eases the movement of the swimmer.

LZR Panels

Speedo’s official website claims that the swimsuit has “ultra thin, ultra powerful, ultra low drag” panels that are embedded “at strategic points on the swimmer’s body”, which are meant to “deliver optimum streamlined shape and drag reduction”.

The Shape is one of the most important factors in drag reduction and the creation of an aerodynamic structure. As we said before, bulky objects are subjected to more drag (and more friction), and streamlined objects (like the shark) are subjected to less drag.

The main reason for this is the flows that are created from the movement of the object inside the liquid. Something very similar happens within winds (in case of a plane) or water (in case of Michael Phelps). The liquid flows either slow the swimmer down or make him (or her!) move more easily.

Aerodymanic flows on an airplane wing. Source: http://www.classicairshows.com/

The above depends on the shape, and that’s what the suit claims to produce: A better aerodynamic shape for the swimmer’s body, depending on key areas that might usually produce more of a problem for such structure.

Core Stabilizer

The “internal Core Stabilizer” is, according to Speedo, like a corset; it “helps [the swimmers] maintain the best body position in the water for longer”.

The human body is not exactly aerodynamic in nature, and part of a swimmer’s training is to learn how to hold himself in the water so his body takes the best aerodynamic shape possible. Maintaining this position – specifically in the water – also takes energy from the swimmer. If, indeed, the swimsuit “holds the swimmer in a corset-like grip”, it can assist him (or her) in the effort to hold their bodies in the proper position, and help them spend that energy on gaining speed instead.

Bonded Seams

The LZR Racer claims to be the “first fully bonded swimsuit.” The problem with seams, usually, is that they have stitches. Stitches are adding mass and weight to the fabric (not only the string itself, but also the fact that stitches require folding the fabric, hence increasing the amount of fabric in that location), and they are also bulkier. Eliminating the stitches will make the suit lighter and without unnecessary ‘bulks’, thereby improving the aerodynamics.

Speedo claims that the LZR Racer has “Ultrasonic welded” seams. The seams are not ’sewn’ but welded, which means that no string is used, and no folds are needed. Ultrasonic welding is a technique that uses high-frequency vibrations on a material under pressure to seamlessly bond two pieces together. The main feature of such technique is that no soldering material or any sort of glue is needed – hence no extra weight, folds or bulks are produced and the suit remains seamless and homogenous.

Ultra Low Profile Zip

This is nothing new; the zipper is “bonded into the suit”, which is common in all swimming suits to make sure that the bulky shape of a zipper doesn’t stand out of the overall shape of the swimmer’s body, and interrupts the water flows.

Unique 3D Three Piece Pattern

The claim on this feature is that the suit is “Dynamically engineered to optimise the shape of the swimmer” (all ye Americans – they mean ‘optimize’). This seems to be mostly a sales pitch; it’s not much different that their “Unique Core Stabiliser” (again, the British spelling).

Summary

Additional Side Note: In order to claim that the suit makes the records rather than the swimmer, or that there is a truly ‘unfair advantage’ for the swimmers who wear this suit, it’s not enough to just see the claims Speedo is making. What needs to be done is have Michael Phelps try out his world-record-breaking with this suit, and with a different suit; if there is an overwhelming difference in the results, perhaps there’s a cause for complaint from other swimmers. Seeing, however, the amount of records (and the overall achievements) in Michael Phelps’ athletic history, claiming that it’s the suit that makes the record might be doing some serious injustice to this obviously-talented swimmer.

All in all, the Speedo RZR Racer swimsuit looks absolutely beautiful, and its claims do fit with reality and physics. As to whether or not it is giving the swimmer an “unfair advantage”, I can’t judge, since I haven’t compared it to any other – perhaps similar – swimsuit in the market.

What I can say quite confidently, however, is that regardless of its features, the person wearing the suit needs to know what he (or she!) is doing. In other words, I could wear this suit ’till my face turns blue (which will probably happen pretty fast, judging from the ‘corset-like grip’) and I’d still never have gotten anywhere close to Michael Phelps’ (or any of the other Olympic swimmers) speed.

That said, I can also summarize this analysis by concluding quite confidently that this suit is, most definitely, better than the one originally worn by Olympic swimmers. They, by the way, used to swim nude.

YouTube Promotional Video

Extra Resources:

• Speedo LZR Racer Official Website: http://www.speedo80.com/lzr-racer/
• What is a Force? http://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/newtlaws/u2l2a.html
• What is drag? (NASA Website): http://www.grc.nasa.gov/WWW/K-12/airplane/drag1.html
• Ultrasonic Welding (from Wikipedia): http://en.wikipedia.org/wiki/Ultrasonic_welding

This was an awesome experiment in an already awesome convention. Don’t forget to check out the JREF website for the DVDs and extras from TAM6. Richard Saunders’ many projects can be checked out through the Australian Skeptics website and the Tank Podcast.

What’s Going On?

When you convert a 3-dimensional object (a face, for example) into a 2-dimentional surface (a page, for example), your end result is stretched and distorted. The reason lies in the curvature of the 3-d object you are trying to copy: The curvatures that give your face the shape it has (your nose, your mouth, your ears), will appear longer when stretched to a flat surface.

What is the Shroud of Turin?

The shroud of Turin is a piece of linen that seems to bear an image of a man lying with his hands in his lap. Some religious groups claim that the image is, in fact, the image of Jesus after his crucifixion.

Whether or not this shroud is real (Scientific examination of the fabric and impressions on it show it is dated much after it is supposed to exist to be authentic), the image that is transcribed on it is interesting. Missing the impression of the face on it is quite hard, and explaining it away with ’simple’ paraedolia doesn’t seem to do it justice.

But if we take our experiment to mind, this image seems to get a different perspective – literally. Take a look at the above drawing, for example, (by Giulio Clovio), depicting Jesus being wrapped in a shroud after his crucifixion. If, truly, this cloth covered the face and body of a man (any man, for that matter), then the impression should not have appeared as a face at all, it should have appeared distorted. A relatively simple test – print out the image, then fold it in half along the nose line – casts some doubt by itself on the existence of a human model for this image.

How are flat maps made?

The creation of a flat map is similar, but not exactly the same as what you have seen in the video. Since distorted maps are quite useless, the drawing of a flat map uses a technique called “Map Projection”. Essentially, the glove is divided into equal squares which are also drawn on a flat surface map. Each square is copied in exact details to the corresponding square in the flat map.

There are several types of such projections, depending on the type of map you need.

An “Equidistant” projection creates a map that has equal distances from the center (equator). A “Zenithal” projection is one that maintains accurate directions.

In general, a flat map is not the accurate depiction of the way our planet looks. It can’t be, because our planet is spherical. But a map projection, at least, makes the conversion slightly more accurate, and easier for our brain to calculate distances and shapes.

More information about the creation of flat maps out of the curvature of our planet can be found in this website (also on the ‘extra resources’ section at the bottom of this page).

Thanks (Original Idea Credit)

Thanks to Edtharan from ScienceForums.net for this idea!

Extra Resources

• JREF Website (James Randi Educational Foundation): http://www.randi.org/
• Australian Skeptics: http://www.skeptics.com.au/
• The Tank Vodcast: http://tankvodcast.wordpress.com/
• The Shroud of Turin: http://www.shroud.com/ and http://en.wikipedia.org/wiki/Shroud_of_Turin
• How maps are formed (3D to 2D): http://www.nationalatlas.gov/articles/mapping/a_projections.html

Science magic! Okay, well, it’s not quite magic, it’s science magic, which means it has (as always) a perfectly good explanation to it. But – can you guess it?

This is a very straight forward demonstration about static electricity, and it is working so well, that it really is fun to do anywhere with a faucet (and a plastic comb..).

What Do You Need?

• A plastic comb or a nylon balloon.
• Dry hair.
• Dry environment (humidity is baaaad)
• A very thin flow of water (about 1 cm thick, or for all you metric-deniers, about 1/16th of an inch).

What’s Going On?

Well, the plastic comb is made of molecules (as is every other matter) that have electrons floating around them. Electrons have a negative charge, and just like a polarized magnet, they are repelled by other negative charges.

When I comb my (dry!) hair with the plastic comb, it collects electrons from the individual strands of hair to itself. About 10 strokes should be enough to make the charge strong enough for the demonstration. The electrons move from my hair strands to the comb and, therefore, lose negative charge. The individual hairs become positive (because they have lost negative charge), the comb becomes negative (because it gained negative charges, in the form of electrons).

The molecules in the water stream are neutral – they have both positive and negative charges, and all their electrons nicely floating around wherever they are supposed to be. When I move the (now negatively charged) comb next to the water stream, the electrons that are closer to the comb are being repelled away. The molecules that are closer to the comb, therefore, become positive, and away from the comb there is more negative charge (more electrons).

The side of the water flow that is closer to the comb is now positively charged, and the comb is negatively charged. Positive and Negative attract one another, and that concept allows the water flow to bend towards the comb.

Voila! instant science magic!

Practical Applications

Static electricity exists in nature, as you may well have noticed in a hot, dry day, trying to open a metal door knob and heard a tiny Bzzzz, followed by an inconvenient sting. Our body exchanges electrons with the surroundings all the time, gathering up and discharging static electricity. But there are more applications and phenomena that are attributed to static electricity:

• Electrostatic Percipitator: This invention is used to clean the air from other particles by inducing electrostatic charge. It’s quite useful, specifically for power plants or big industrial facilities.
• Xerography: this is a photocopying technique developed in the late 1930s. It distributes a uniform electrostatic charge on a surface of a drum. The image is then lit through (so wherever there is color, the surface remains unlit) on a grid on top of the charged drum. The light dissipates the charge, so the grid remains charged only where the image is printed. Then, carrier particles are mixed through the drum and “soaked” into the paper – so they “stick” where the charge exists, and therefore duplicate the image.

More References

• This demonstration on about.com: http://chemistry.about.com/od/chemistryexperiments/ht/bendwater.htm
• This demonstration on sciencebob.com http://www.sciencebob.com/experiments/bendwater.html
• This demonstration on SciFun@Wisconsin university: http://scifun.chem.wisc.edu/homeexpts/BENDWATER.html
• This demonstration on Science Made Fun: http://www.sciencemadesimple.co.uk/page30g.html
• Wikipedia entry on Static Electricity: http://en.wikipedia.org/wiki/Static_electricity

Well, this is going to be sweet, short and to the point: Fire in closed spaces can really suck.

Ha, I was dying to use that pun for a while now, and here I had the chance. This experiment is a really short and sweet one, and can join your mental arsenal of “party tricks” for the partying geeks. It can really impress anyone, and from now on – you are going to know what makes this happen.

Ready?

Air is a fascinating thing, but sometimes it can be an obstacle. We will see that in future experiments, where the existence of air (or, more precisely, of oxygen) can hinder an experiment and render it unexperimentable. … Right. I think I need a dictionary replacement.

Warning!

In case this isn’t completely clear, I am going to point out that since we are dealing with a live and exposed flame, the use of any high-percentage alcohol is absolutely not recommended.

I hope that is obvious, but in case it’s not – ALCOHOL IS FLAMMABLE. SO IS GASOLINE. Don’t do something very stupid, don’t use flammable liquids in this experiment!

(Thanks to RedShiftScience for pointing out people might not find this obvious.)

Corrections!

Before I go on to corrections, let me say a word about getting things wrong: Human beings are usually emotional entities, and as such, we tend to take things personally. Science is supposed to be empirical, void from emotions. How do you connect the two? Using the scientific method.

There is no shame in getting things wrong. We are only humans.

The best thing about science and experimentation is to have other people think about things, analyze them, and criticize your work. I not only enjoy that, I think it’s a necessary part of science.

In my video, I explained a few things incompletely, and some even seemed to have come across bluntly wrong (aaa! matter is not created out of nothing, and it does not disappear! in failing to mention that, I sounded like this experiment defies the laws of thermodynamics!). So, I am hereby correcting, adding and subtracting to what I said. I tried to do that well in this post — and then Shane Killian — who noticed this error first – posted a video reply.

So now I can just post it here instead of doing it all over again. Cheers, Shane, GREAT job, and thanks a lot for the correction!

Don’t ever be afraid to try just because you’re afraid to make a mistake.

What is a Vacuum?

A vacuum is a volume of space with no matter in it, and a zero atmospheric pressure. That is the formal definition. That said, there are no places in nature that have absolute vacuum.

We tend to call “Outer Space” a vacuum, but in reality, it is filled with particles, which makes it have some sort of matter, which means it’s not a complete vacuum. But it’s close enough.

Since a vacuum is supposed to have 0 atmospheric pressure (or as close as possible), it “sucks” into it anything that has a different – and higher – pressure. This is due to the tendency to have a balance of pressures — different pressures will try to balance one another, so the lower pressure environment will “suck” matter from the higher pressure environment until both environment are at a balance.

That’s why you see people get sucked out of the airlock in sci-fi movies. It’s one of those things movies got right.

In our experiment, we lowered the pressure and created a semi-vacuum inside the glass, and in turn, it sucked up the liquid around it. Or, more specifically -

What’s going on here?

With this cool little party trick, we are creating a “semi” vacuum inside the clear glass by consuming the oxygen inside it. When the fire consumes the oxygen molecules, it “vacates” a place for – well – whatever else. The pressure inside the glass rises, and since it isn’t sealed, it sucks whatever it is standing on

CORRECTION: The pressure inside the glass increases as the fire heats up the molecules. Oxygen is being “consumed” by the fire, that produces Carbon Dioxide (the matter itself remains, no matter is mysteriously ‘vanishing’ or ‘created’ out of nothing!). But now, the pressures are different and therefore the water outside the glass are pushed inwards — the lower pressure of the INSIDE ’sucks in’ the liquid around it under the pressure stabilizes.

Thanks to Shane Killian for the correction.

If I were to use a jar and sealed it well while the candle inside fed on the oxygen, the cap would have been “sucked” into the jar mouth, and the jar would have been sealed. Since I am not using a cap, but rather putting the glass on top of liquid (that can “pass through” the edge of the cup), the liquid is sucked inside the glass and stays there, until I release the pressure and allow air in.

This is a really sweet, cool and short experiment, but the best thing about it is that it will help us produce home-style vacuum setting for other experiments. And so, it’s good to know.

Plus, it’s fun. And edible. Woo hoo.

Practical Applications

• First, this is a cool and easy way of creating home-made semi-vacuum setting, for whatever other experiment you will need. We’ll use this in the future.
• Here’s a cool practical trick to preserve food for you to consider, though it isn’t precisely the same method, it uses a similar point: If you cook something and wish to save some for later in sealed jars, the best way of doing that is seal the jar while the food is still hot. Once sealed, whatever air inside the jar is trapped, and when the food cools, the air compresses and tightens the jar cap so that it is relatively sealed from the outside. Food will last longer this way, but you will have a bit of a harder time opening the jar.
• Impress people in parties, collect on bets, and dazzle your dates. What else do you want?

Resources:

• Another video with the same point: http://www.metacafe.com/watch/334272/physics_experiment_liquid_suction/
• And another: http://www.metacafe.com/watch/540641/bored_try_this_easy_experiment/
• Vacuum: http://en.wikipedia.org/wiki/Vacuum
• The Human Body in Space (Vacuum): http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970603.html

Well, this is more of a “Show off your geektitude” physics trick that will amaze and enchant your buddies anywhere! Okay, well, maybe not anywhere. Or anyone. But it is geeky, I promise. And will get you some attention.

And it’s cool.

And it’s useful. For parties.

I can switch the contents of two glasses without using a third glass. Yes, I can. Don’t believe me? Well – When in doubt, try it out!

So. Anyone who asks a bartender for anything “on the rocks” knows that alcohol and water do not mix. Not properly, anyways. Not without insistent help. The alcohol always ends up floating on top of the excess water that melted off of the ice. But why?

Well, that has to do with the density of both liquids. Dense materials sink, and less-dense materials float. Water is denser than alcohol, so the alcohol floats on top of the water.

Density also changes with temperature. Water is denser when it’s cold. In higher temperature, the density is lower. Hotter water will always “want” to rise up above colder water. And we’re using this property in this nifty trick. Did I say it was cool?

What is Density?

Density is the measurement of mass per unit of volume. Put simply, it is the amount of particles within a specific space in the material used. A bar of gold will have a lot of particles within 1cm cube volume, while water fume will have very few in the same space. So gold is denser than fume. Which is why we choose to wear it as jewelry.

In physics, the general formula is represented by p=m/v, which means that density is mass per volume. If you know the mass and you know the volume (both quite easy to figure out), you can find the density of objects. This is another cool experiment that will be coming up in the future, and you can try it out yourselves with anything, really, as long as you know its volume (size) and weight (and can figure out the mass). Just be careful who you ask..

Why leave a small hole between the cups?

We don’t want our two liquids to mix, we want them to “switch”. When you leave a tiny hole between both cups, a stream of liquid from the bottom cup is flowing upwards, because it’s lighter, and is replaced by a stream of liquid from the top cup (the ‘heavier’ liquid). If we completely discard of our separator, the liquids will simply mix, and we will have diluted alcohol. Or room-temperature water.

When the process is allowed to happen slowly, after a few minutes, both cups are completely filled with the opposite liquids.

Maaaaaagic! Well, no. Physics.

I mean… Phyyyyyyyyyyyyyyyyyysics!

Materials needed for the Experiment

• Two cups of the same size.
• Alcohol
• Water.
• Credit Card / MTA Card / Cardboard.

Don’t drink and drive.
We will go over momentum in future experiments, but this is one thing you all should know.

Practical Applications

You mean other than being the star of a party? Oh, okay okay, here are a few practical applications for knowing the density and buoyancy of liquids:

• Buoyancy! The density of liquids affect their buoyancy. The lowest dry point on earth, for example, the Dead Sea, has a very high salinity, which makes its density a lot higher than regular ocean water. As a result, people (and other objects) float. Without trying.
• Distant Stars: Astronomers can calculate the density of stars from their mass and volume, and understand better about the process that is “running” the star.

Resources

• Water Density: http://www.4physics.com/phy_demo/Galileo_thermometer/galileo-thermometer-d.html
• Water’s Density and the Relation to Temperature: http://www.simetric.co.uk/si_water.htm
• Oil floats on Water: http://www.physlink.com/Education/AskExperts/ae105.cfm

Today we have a lot of sophisticated (and simple) methods of calculating the curvature and size of the earth. But how did humanity figure this out in the first place? I mean.. it’s so easy, without the help of satellites, airplanes and Jules Verne, to look at the flat horizon and mistake the earth for a flat table top. How could anyone figure out not only that the world is not flat, but also calculate the size of its radius?

Well, when in doubt, try it out. Hey.. I think I like that motto. It’s rhyming, and rhymes are usually true. Just ask Dr Seuss.

Plus.. it works!

So, a long time ago, people believed the earth was flat, and that if someone was to go away off to the horizon, he (or she) would fall off the end of it.

We look at this ancient concept as ridiculous today. We al know that the flatness of the horizon is an illusion. We have more than enough proof today to see absolutely that the world is definitely curved, but it is for the ingenuity of people like Erastosthenes of Cyrene that humanity knew about this so long ago.

Eratosthenes was a greek scholar that lived in 275-194 B.C. in Alexandria (Egypt). Some even say he was the curator of the library of Alexandria. One day, he had a bright idea. Actully, it wasn’t just any day, it was the summer solstice, and it wasn’t just any idea, it was a brilliant experiment. But, let’s not dwell on the tiny details. He was very smart and he acted on it.

He received word that on that summer solstice day the sun is reflected perfectly in a deep well in Syene. But at the same time and same day, in Alexandria, the sun wasn’t reflected perfectly in the same type of well. Why?

It occured to him that the only way that could have happened is if the earth was not flat. Using simple trigonometry, he managed to calculate the radius and diameter of the earth. In this experiment, we do the same, only we use a Pummelo. Because it’s easier. And tastier.

Materials Needed for the Experiment:

• Any type of round, big, (preferably tasty) fruit. I used a Red Pummelo, but a Watermelon will work too.
• Small sticks to simulate Eratosthenes’ big sticks.
• One bright and focused lamp.
• A ruler.
• A sharpie.

The pummelo represents the earth. Nevermind it isn’t perfectly round – the earth isn’t either, and we are only trying to see the method, not actually calculate the radius of the fruit.

Error Margin

Wow, there’s a lot of reasons to have that, but they are less important than you would have thought. If our goal was to accurately calculate the circumference of the earth (or the fruit) then our method is not perfect at all.

The fruit was far from being spherical. It was almost cubic at some pionts, flat at others, and had lots of bumps on it. The radius on one small section of it is not necessarily the radius on another point on it. So, error margin in that matter is quite obvious.

But Eratosthenes’ method is important not necessarily because of the numerical result, but for its significance in discovering the world is a sphere. Remember, Galileo Galilei almost lost his head over this idea (among others), and that was about 2000 years after Eratosthenes.

Not to mention many of us learned the (sadly, very common) misconception that Christopher Columbus is the explorer who discovered the world is round.

Wrong!!

Humanity was Smarter Than That a long time ago, and Eratosthenes’ ingenious way of estimating the circumference verifies it completely.

Resources:

Eratosthenes:

• http://outreach.as.utexas.edu/marykay/assignments/eratos1.html
• http://scienceworld.wolfram.com/biography/Eratosthenes.html
• http://www.eranet.gr/eratosthenes/html/eoc.html

Earth Radius:

• http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html
• http://en.wikipedia.org/wiki/Earth_radius

Trigonometry Reminder:

• http://www.clarku.edu/~djoyce/trig/right.html
• http://oakroadsystems.com/math/trig10.htm

Flat Earth (not!):

• http://www.badastronomy.com/bablog/2007/09/19/how-wrong-is-the-flat-earth/
• “Flat Earth Society” (from “The Skeptic’s Guide to the Universe” blog: http://www.theskepticsguide.org/sgublog/?p=115

Red Pummelo is good for you:

• http://www.all-creatures.org/recipes/i-pummelo-red.html

I wonder what would their world look like if they knew that light can be bent. Well, in huge distances (like space) light is bent with gravit, which is pretty cool, but it takes a big body of mass and quite a large distance to do that. I am not going to travel light years to see light bend. I’m going to do it in my own bathroom. You can too. In your own bathroom.

So what actually happens with light to cause it to “bend”? In short distances, light travels in straight lines, and if they are otherwise undisturbed, they will go on forever. Or at least for a really really really really long time. That’s how we see distant stars, their light travels huge distances and reaches our telescopes (or eyes, if the night is clear).

Using the principle of refraction, we can simulate a situation where a light beam is ‘bent’. Think about a bunch of mirrors, each refracting the light in a slight angle towards another mirror – eventually directing a beam of light at a completely different angle. That seems easy enough, and – unsurprisingly – that is exactly what is happening within the flow of water.

Materials for the Experiment

• A Plastic Bottle – preferably clear and empty.
• Duct Tape. (I used blue, you can use whichever color you feel like).
• Laser Pen, or other directed light source.
• Water.

Preparations

Take the plastic bottle and poke a hole in it with a pin. I recommend expanding it a bit, the hole in my bottle was about 2mm in radius. The trick is to create a large enough hole to encompase the entire laser beam, but not large enough to have the water just pour out uncontrollably. It took me about 3 attempts to get this straight. Err.. bent.

Now, cover the hole with the duct tape and poke another hole through the not-for-long sealed hole. The duct tape is not absolutely necessary, but it will help directing the laser ray towards the hole. You would be amazed how difficult it can be to aim when water is pouring out on top of you…

Seal the hole with your finger and fill the bottle with water. When it’s full, close the cap. The pressure inside the bottle will prevent the water from coming out through the hole – as long as you are careful not to squeeze the bottle. Or drop it. Or tilt it too fast…. okay, maybe you should keep your finger on the hole anyway.

Put the bottle somewhere wet (or that you wouldn’t mind getting wet, like a bath tub), turn your laser beam on and point it at the hole. Release the cap.

Water should be coming out now, and if you aim your laser light properly, they should refract the beam towards the surface and appear slightly reddish (or.. whatever color your laser beam is).

Real Life Applications

• Optic Cables: Spread over the ocean and land, optic cables direct light from one point to another using this principle. No, they are not made of water, they’re made of a matterial that is, actually, better refracting (light beams don’t ‘come out’ of the cable mid-way, usually, only at its ends). This means that the light does not lose energy along the way, and reaches the destination in the speed of light. Which is fast. Very fast. Yay for optic cables.

Resources

• Light Refraction: http://www.ps.missouri.edu/rickspage/refract/refraction.html
• Refraction of Light: http://sol.sci.uop.edu/~jfalward/refraction/refraction.html
• Full Bottle, Hole, No Leak: http://www.newton.dep.anl.gov/askasci/phy00/phy00946.htm
• howtoons: http://www.instructables.com/id/Bending-Light/